1. Field of the Invention
The present invention relates generally to apparatus for dispensing filament on a missile or other airborne vehicle to establish a data link with apparatus at the launching site, and, more particularly, to such filament dispensing apparatus which does not require adhesive for maintaining wound pack integrity and has improved filament payout characteristics.
2. Description of Related Art
Many present day weapon systems include a launched missile having a wire or optical fiber data link, one end of which is connected to on-board missile control apparatus while the other end pays out at a high rate of speed to maintain interconnection with other apparatus at the launch site.
A successful data link must meet several criteria. A first one is that filament payout must be accomplished with an acceptably lower tension on the filament to avoid breakage, or, in the case of an optical fiber, to prevent what is termed "micro bending" which reduces the quality and efficiency of signal transmission. Also, the filament wound package or pack must be stable so as to enable storage without having the winding collapse from its wound configuration. In addition, the winding pack should be as dense and compact as possible so that it will take up no more space than absolutely necessary.
One frequently encountered present day filament dispenser consists of a generally cylindrical tapered canister fixedly located at the aft end of the vehicle with its longitudinal axis generally parallel to that of the vehicle. During payout, the filament is directly peeled off the end of the canister paying out in a somewhat extended helical configuration. Another known dispenser includes a cylindrical canister with the filament wound so as to be able to effect payout from the inside of the filament package, this form being especially advantageous for torpedo and sonobuoy applications.
To maintain the geometric integrity of a filament pack it has been usual practice to apply an adhesive to the filament during winding or to the pack itself. It would be desirable, however, to be able to eliminate the use of adhesive since it is a dominant payout speed limiting factor in stationary dispensers where the peel bend stress induced by the force required to fracture the adhesive binder can be substantial. There is also a continuing problem with adhesive aging which means that where there is to be storage for any considerable length of time, there is a serious concern that deterioration will make it incapable of functioning.
Another matter of concern is the tendency for production of a whirling motion of a filament on dispensing from a moving vehicle which results in a further requirement that the dispenser be mounted at the aft end of the vehicle, or that it be mounted free from possible obstructions. It would, therefore, be highly desirable to be able to damp the helix formed in a dispensed filament and, to the extent possible, obtain a helix controlled payout. If this can be achieved then there would be greater choice in canister location and direction of payout.